Hi again, Tania
You can do it manually, using a little math. Or you can use a Position Size Calculator to do the math for you.
Personally, I believe it’s good to know how to do this manually, even if you take the easy route in the future and let the Calculator do it for you.
Some of these position size calculations are so easy, you can do them in your head. Some are more difficult. The difference, as rhody has pointed out, depends on [B]whether your account currency matches the quote-currency (cross-currency) of the pair you are trading.[/B]
Examples: Your account currency is USD. Your account currency matches the quote-currency in EUR/USD, GBP/USD, AUD/USD, etc. But, it does not match the quote-currency in USD/CAD, USD/JPY, EUR/GBP, GBP/JPY, etc.
Let’s do a position-size calculation by hand, and let’s start with an easy one.
Let’s say you want to trade [B]EUR/USD[/B] in your $1,000 account, with 2% risk, and a 60-pip SL.
How large a position can you trade?
We know that your account currency matches the quote-currency in this pair, so we also know —
1 pip is worth $10 in a standard lot (100,000 units of BASE currency)
1 pip is worth $1 in a mini-lot (10,000 units of BASE currency)
1 pip is worth $0.10 in a micro-lot (1,000 units of BASE currency)
1 pip is worth $0.01 in a nano-lot (100 units of BASE currency) and
1 pip is worth $0.0001 (that’s 1/100 of 1¢) PER UNIT of BASE currency
Oanda lets you trade in individual units, so we will use that last figure: 1 pip = $0.0001
If you get stopped out, your 60-pip loss will cost you $20 (that’s 2% of your balance). So, if 60 pips = $20 (in this trade), then how much is 1 pip (in this trade)? The answer is $20 / 60 = $0.33333… (that is, 33 and 1/3 cents).
If 1 pip in this trade is worth $0.33333…, and 1 pip is also worth $0.0001 per unit, then how many units are in this trade? The answer is $0.33333 / $0.0001 = [B]3,333 units[/B] (dropping the fraction of a unit).
So, you can trade 3,333 units of EUR/USD (or any other pair in which the USD is the quote-currency), with your $1,000 account, 2% risk, and 60-pip SL.
Let’s use the Position Size Calculator to check this result.
We pull up the Calculator, and enter the following inputs:
Account Currency: USD
Account Balance: 1000
Risk Percentage: 2
Stop-Loss in Pips: 60
Currency Pair: EUR/USD (from the drop-down menu)
Click on [I]Calculate,[/I] and we get these results (which match what we calculated manually):
Amount at Risk: 20 USD
Position Size: 3333 units
Standard Lots: 0
Mini Lots: 0
Micro Lots: 3
Clearly, the result you want is [B]3333 units[/B] (because you will be trading units, not micro-lots).
Here’s a homework assignment for you:
Use the Position Size Calculator to determine how many units of USD/JPY, EUR/AUD, and GBP/NZD you can trade, assuming $1,000 balance, 2% risk, and 60-pip SL, in each trade. Notice that the Calculator is going to ask you for the current price of the quote-currency in each case (because in each of these trades, the quote-currency does not match your account currency).
.